Solve the problem.
-Two friends decide to meet in Chicago to attend a Cubʹs baseball game. Rob travels 78 miles in the sametime that Carl travels 64 miles. Robʹs trip uses more interstate highways and he can average 7 mph morethan Carl. What is Robʹs average speed?
A)39 mph
B)32 mph
C)43 mph
D)35 mph

Question

Quizplus · Accepted Answer

Rob's average speed is 39 mph. Since Rob travels 78 miles and Carl travels 64 miles in the same amount of time, and Rob averages 7 mph more than Carl, we can set up the equation 78/(r+7) = 64/r, where r is Carl's average speed. Solving for r gives us Carl's speed as 32 mph, so Rob's speed is 32 + 7 = 39 mph.

Solve the Problem. -Two Friends Decide to Meet in Chicago to Attend a to Attend